This relates generally to graphics processing and particularly to techniques for rendering transparent images.
Graphics processing continues to address the problem of rendering transparent objects in real-time. Renderers determine the amount of light transmitted by all objects between a given fragment and the viewer. Ray tracers compute this quantity as a result of tracing rays from the viewing position into the scene. However, rasterizers generate fragments in any order, collect transmittance information from each fragment and use it to determine the final pixel color after all partial occlusions are determined. There are a number of exact and approximate methods for handling transparency in the rasterizer.
If a fragment is at a distance zi from the viewer, has color ci and transmittance 1−αi, and vis(z) represents a transmittance between the fragment in the viewer, this contribution is given by:ciαivis(zi)  (1)with the total contribution of many overlapping fragments given by:Σi=1nciαivis(zi)  (2)While the transmittance and color of each fragment are known during the fragment shading, computing transmittance vis(zi) is the focus of rasterization transparency algorithms.